Method and apparatus for monitoring material removal tool performance using endpoint time removal rate determination

Abstract

A method for monitoring the performance of a material removal tool includes providing a wafer having at least one process layer formed thereon; measuring the thickness of the process layer; removing at least a portion of the process layer in the material removal tool until an endpoint of the removal process is reached; determining a removal rate based on the measured thickness of the process layer and a duration of the removal process until the endpoint is reached; and comparing the determined removal rate to an expected removal rate to monitor the performance of the material removal tool. A processing line includes a metrology tool, a material removal tool, and a process controller. The metrology tool is adapted to measure a thickness of a process layer formed on a wafer. The material removal tool is adapted to remove at least a portion of the process layer until an endpoint is reached. The process controller is adapted to determine a removal rate based on the measured thickness of the process layer and a duration of the removal process until the endpoint is reached and compare the determined removal rate to an expected removal rate to monitor the performance of the material removal tool.

What is claimed:  
     
       1. A method for monitoring the performance of a material removal tool, comprising: 
       providing a wafer having at least one process layer formed thereon;  
       measuring the thickness of the process layer;  
       removing at least a portion of the process layer in the material removal tool until an endpoint of the removal process is reached;  
       determining a removal rate based on the measured thickness of the process layer and a duration of the removal process until the endpoint is reached; and  
       comparing the determined removal rate to an expected removal rate to monitor the performance of the material removal tool.  
     
     
       2. The method of  claim 1 , further comprising initiating an automatic corrective action in response to identifying a deviation between the determined removal rate and the expected removal rate. 
     
     
       3. The method of  claim 2 , wherein initiating the automatic corrective action comprises sending an alert message to an operator of the material removal tool. 
     
     
       4. The method of  claim 2 , wherein initiating the automatic corrective action comprises logging the material removal tool out of service. 
     
     
       5. The method of  claim 2 , wherein initiating the automatic corrective action comprises adjusting the operating recipe of the material removal tool to reduce the deviation. 
     
     
       6. The method of  claim 1 , wherein comparing the determined removal rate to an expected removal rate comprises comparing the determined removal rate to at least one control limit and monitoring the performance of the material removal tool comprises identifying a degraded condition in response to the determined removal rate violating the control limit. 
     
     
       7. The method of  claim 1 , wherein comparing the determined removal rate to an expected removal rate comprises comparing the determined removal rate to an upper control limit and a lower control limit and monitoring the performance of the material removal tool comprises identifying a degraded condition in response to the determined removal rate violating at least one of the upper and lower control limits. 
     
     
       8. The method of  claim 1 , wherein comparing the determined removal rate to an expected removal rate comprises generating a predicted removal rate using a model of the material removal tool performance. 
     
     
       9. The method of  claim 1 , wherein removing at least a portion of the process layer in the material removal tool until an endpoint of the removal process is reached comprises removing the process layer until an endpoint associated with complete removal of the process layer is reached. 
     
     
       10. The method of  claim 1 , further comprising measuring a remaining thickness of the process layer, wherein determining the removal rate comprises determining the removal rate based on the measured thickness of the process layer, the measured remaining thickness of the process layer, and the duration of the removal process until the endpoint is reached. 
     
     
       11. A method for monitoring the performance of a material removal tool adapted to remove at least a portion of a process layer formed on a wafer, comprising: 
       storing measured thicknesses of the process layers for a plurality of the wafers;  
       storing endpoint times for the plurality of wafers processed in the material removal tool;  
       determining removal rates based on the measured thicknesses and the endpoint times; and  
       comparing the determined removal rates to an expected removal rate to monitor the performance of the material removal tool.  
     
     
       12. The method of  claim 11 , further comprising initiating an automatic corrective action in response to identifying a deviation between the determined removal rate and the expected removal rate. 
     
     
       13. The method of  claim 12 , wherein initiating the automatic corrective action comprises sending an alert message to an operator of the material removal tool. 
     
     
       14. The method of  claim 12 , wherein initiating the automatic corrective action comprises logging the material removal tool out of service. 
     
     
       15. The method of  claim 11 , wherein comparing the determined removal rates to an expected removal rate comprises comparing the determined removal rates to at least one control limit and monitoring the performance of the material removal tool comprises identifying a degraded condition in response to at least one of the determined removal rates violating the control limit. 
     
     
       16. The method of  claim 11 , wherein comparing the determined removal rates to an expected removal rate comprises comparing the determined removal rates to an upper control limit and a lower control limit and monitoring the performance of the material removal tool comprises identifying a degraded condition in response to at least one of the determined removal rates violating at least one of the upper and lower control limits. 
     
     
       17. The method of  claim 11 , wherein comparing the determined removal rate to an expected removal rate comprises generating a predicted removal rate using a model of the material removal tool performance. 
     
     
       18. The method of  claim 11 , wherein storing measured thicknesses of the process layers for a plurality of the wafers includes storing measured remaining thicknesses of the process layer for the plurality of wafers processed in the material removal tool. 
     
     
       19. A processing line, comprising: 
       a metrology tool adapted to measure a thickness of a process layer formed on a wafer;  
       a material removal tool adapted to remove at least a portion of the process layer until an endpoint is reached; and  
       a process controller adapted to determine a removal rate based on the measured thickness of the process layer and a duration of the removal process until the endpoint is reached and compare the determined removal rate to an expected removal rate to monitor the performance of the material removal tool.  
     
     
       20. The processing line of  claim 19 , wherein the process controller is further adapted to initiate an automatic corrective action in response to identifying a deviation between the determined removal rate and the expected removal rate. 
     
     
       21. The processing line of  claim 20 , wherein the process controller is further adapted to send an alert message to an operator of the material removal tool. 
     
     
       22. The processing line of  claim 20 , wherein the process controller is further adapted to log the material removal tool out of service. 
     
     
       23. The processing line of  claim 20 , wherein the process controller is further adapted to adjusting the operating recipe of the material removal tool to reduce the deviation. 
     
     
       24. The processing line of  claim 20 , wherein the process controller is further adapted to compare the determined removal rate to at least one control limit and identify a degraded condition in response to the determined removal rate violating the control limit. 
     
     
       25. The processing line of  claim 19 , wherein the process controller is further adapted to compare the determined removal rate to an upper control limit and a lower control limit and identify a degraded condition in response to the determined removal rate violating at least one of the upper and lower control limits. 
     
     
       26. The processing line of  claim 19 , wherein the process controller is further adapted to generate a predicted removal rate using a model of the material removal tool performance. 
     
     
       27. The processing line of  claim 19 , wherein the endpoint times are associated with complete removal of the process layer. 
     
     
       28. The processing line of  claim 19 , further comprising a second metrology tool adapted to measure a remaining thickness of the process layer, wherein the process controller is adapted to determine the removal rate based on the measured thickness of the process layer, the measured remaining thickness of the process layer, and the duration of the removal process until the endpoint is reached. 
     
     
       29. A processing line, comprising: 
       means for measuring the thickness of a process layer formed on a wafer;  
       means for removing at least a portion of the process layer until an endpoint time is reached;  
       means for determining a removal rate based on the measured thickness of the process layer and the endpoint time; and  
       means for comparing the determined removal rate to an expected removal rate to monitor the performance of a material removal tool.  
     
     
       30. A method for monitoring the performance of a material removal tool, comprising: 
       providing a wafer having at least one process layer formed thereon;  
       measuring the thickness of the process layer;  
       removing at least a portion of the process layer in the material removal tool until an endpoint of the removal process is reached;  
       measuring the thickness of a remaining portion of the process layer;  
       determining a removal rate based on the measured thickness of the process layer, the measured thickness of the remaining portion, and a duration of the removal process until the endpoint is reached; and  
       comparing the determined removal rate to an expected removal rate to monitor the performance of the material removal tool.  
     
     
       31. The method of  claim 30 , further comprising initiating an automatic corrective action in response to identifying a deviation between the determined removal rate and the expected removal rate. 
     
     
       32. The method of  claim 31 , wherein initiating the automatic corrective action comprises sending an alert message to an operator of the material removal tool. 
     
     
       33. The method of  claim 31 , wherein initiating the automatic corrective action comprises logging the material removal tool out of service. 
     
     
       34. The method of  claim 31 , wherein initiating the automatic corrective action comprises adjusting the operating recipe of the material removal tool to reduce the deviation. 
     
     
       35. The method of  claim 30 , wherein comparing the determined removal rate to an expected removal rate comprises comparing the determined removal rate to at least one control limit and monitoring the performance of the material removal tool comprises identifying a degraded condition in response to the determined removal rate violating the control limit. 
     
     
       36. The method of  claim 30 , wherein comparing the determined removal rate to an expected removal rate comprises comparing the determined removal rate to an upper control limit and a lower control limit and monitoring the performance of the material removal tool comprises identifying a degraded condition in response to the determined removal rate violating at least one of the upper and lower control limits. 
     
     
       37. The method of  claim 30 , wherein comparing the determined removal rate to an expected removal rate comprises generating a predicted removal rate using a model of the material removal tool performance.